These clever doorbells induces power to send a signal (and flash an led) by the mechanical press on the button! So no more batteries!
I bought two different types. With different pros and cons, and luckily they are so related that the buttons for one, can be used on the other!
I bought one first with a fairly neutral ringer and 40mm wide doorbells. But that was too wide to place conveniently between the door and the wall…
So bought another type that is only 33mm wide that fitted perfectly in the available 36mm…
Type “Cacazi”
I bought them from here.
These are nice looking bells, but as mentioned a bit wide.
The ringer offers 60 ring tones, 5 volume levels, and can have individual ring tones for at the least five buttons! (I only tried five!)
Type “Cerhot”
(I can not help reading this as a mix of German and English: “Sehr hot”)
I bought them from here.
This one has the 33mm buttons.
The ringer unit is also more compact, and has a display with the temperature. But it flickers at 50Hz, so quite annoying! AND it has only ONE common ringtone, for all (up to 5) bells. 38 to choose from and some are fairly neutral.